What is parliamentary sovereignty?

Parliamentary sovereignty is the principle that Parliament is the supreme law-making body in the UK. It can make or repeal any law, and no court can strike down an Act of Parliament. It also means no Parliament can bind its successors. It is the central principle of the UK's uncodified constitution.

The principle was set out by the lawyer A. V. Dicey in the 19th century. It grew from the struggles between Crown and Parliament in the 1600s and the Bill of Rights of 1689. Because the UK has no single written constitution, there is no higher law that Parliament must obey, unlike in the United States. Courts interpret laws. Constitutional experts still debate its limits.

Some developments have complicated the picture. While the UK was in the European Union, EU law took priority over conflicting UK law. The Human Rights Act 1998 lets courts declare a law incompatible with human rights, but not overturn it. Devolution handed powers to Scotland, Wales and Northern Ireland, though Westminster kept the legal right to legislate. Ministers must obey too.

Brexit was often framed as restoring parliamentary sovereignty. In the Miller cases of 2017 and 2019, the Supreme Court upheld Parliament's role against the government. Some argue the UK should adopt a written constitution with entrenched rights. Others say parliamentary sovereignty keeps power with elected representatives rather than judges. The debate became sharper after the 2019 prorogation ruling, which found the government had acted unlawfully.